In accordance with the spread of owner-driven cars due to improvement of a quality of life, the owner-driven car has now become a daily necessity. Therefore, research into an anti-theft apparatus of the own-driven car and various technologies of opening a door of the vehicle and starting the vehicle has been continuously conducted. An example of this research includes a keyless entry scheme and a keyless start scheme.
The keyless entry scheme indicates a scheme of opening or closing the door without performing a separate manipulation of a key or a remote controller by a driver. In the keyless entry scheme, when the driver possesses the key on his/her body, the key and an electronic authentication apparatus in the vehicle transmit and receive data to and from each other, and a locking module of the door is automatically operated when authentication is made.
A smart key is used in this system, authentication information on a vehicle and a radio frequency (RF) signal transmitting and receiving apparatus are provided in the smart key, and the vehicle includes several antennae provided at an inner side and an outer side thereof to communicate with the smart key.
In order to implement a smart key system, at most ten antennae having low frequency (125 kHz or 134 kHz) field characteristics are used.
The antennae of the smart key system are used to sense the smart key outside the vehicle.
This electric wave belongs to a low frequency region, and since an electric wave generation region is within about 1 m from the vehicle, the antennae may sense the smart key and communicate with the smart key in only this region.
Even though the antennae used in the smart key system have the same hardware configuration, the number of antennae that are installed is plural, such that a coat required for manufacturing the antennae is unnecessary.